Mental deterioration in the aged is associated with microscopically visible deterations of brain tissue. Some of these changes, dendritic loss and axonal swelling similar to those found in senile plaques, have been found to occur in rat brain as a result of dietary deficiency of vitamin B-6 and/or copper. Additional changes associated with senility, amyloid deposit and neurofibrillary tangles, may occur in response to deficiency of additional nutrients. Such multiple deficiencies are the rule rather than the exception in humans. Identification of a group of deficiencies causing tissue changes characteristic of senility would readily lead to methods of treatment and prevention of the condition. It is proposed to attempt to develop an animal model for study of senility of the Alzheimer type by superimposing deficiency of folate and/or magnesium upon deficiency of vitamin B-6 and/or copper. These nutrients are chosen because they have been associated with brain pathology or symptoms suggesting central nervous system abnormality and because they are often deficient in human food intakes. Young rats, which are used to facilitate rapid production of the deficient state, will be fed the diets for 3 months and their brains will be examined by electron microscopy, Golgi impregnation and staining of paraffin sections for senile plaques and neurofibrillary degeneration. Success would provide strong support for the concept of a nutritional etiology for brain cell changes of the Alzheimer type and would warrant further studies which could ultimately lead to treatment or prevention of senility.